1. Field of the Invention
This invention relates to a thermal or radiation curable liquid prepolymer, formulations containing same and processes for using same to form printing plates, coatings, adhesives or sealants. More particularly, this invention is directed to a liquid prepolymer comprising a (meth)acrylated polymeric hydrocarbon maleate, either per se or formulated with mono- or multi-functional unsaturated monomers and either a thermal initiator or photoinitiator which, on exposure to heat or UV or high energy ionizing radiation, forms a cured material utilizable as a printing plate, coating, adhesive or sealant.
2. Description of the Prior Art
Photocurable compositions are well known in the art for forming printing plates, coatings, adhesives or sealants. In particular, in the printing plate art, such compositions have made vast inroads in letterpress, offset lithographic and flexographic printing. Initially, the photopolymerizable compositions such as taught in U.S. Pat. No. 2,760,863 required the use of organic solvents for development. However, due to the toxicity, high volatility and low flash point of commercial organic solvents, their use often gave rise to hazardous conditions and created a pollution problem.
Subsequently, U.S. Pat. No. 4,137,081 directed to liquid terminal, olefinic, unsaturated linear polymers in combination with ethylenically unsaturated monomers, a stabilizer and a photoinitiator, resulted in printing plates in which the unirradiated portions can be removed with dilute aqueous solutions of a detergent. However, such materials have a tacky surface which causes the spaces in the relief to fill with ink thereby giving poor printing quality. Japanese No. 82-967 teaches a polymer image forming process comprising exposing a light sensitive composition prepared from a diene polymer having photopolymerizable unsaturated groups, a photopolymerizable vinyl monomer, a photoinitiator and, optionally, a thermal polymerization inhibitor, to UV radiation imagewise and, thereafter, removing the unexposed part of the composition to form a printing plate. The diene polymer such as polybutadiene can have polymerizable unsaturated bonds and be chain extended with epichlorohydrin.